Plastic containers made of a polyethylene terephthalate or the like have been widely placed in practical use as containers for containing beverages. Preforms from which the plastic containers are obtained are, generally, formed by using an injection-forming machine. In recent years, however, attempts have been made to form the preforms by using a compression-forming machine, and a variety of improvements have been made therefor. In carrying out the compression forming, a molten resin extruded from an extrusion opening of an extrusion nozzle is supplied (conveyed) to the compression-forming machine in a manner as described below.
The synthetic resin heated and melted in the extruder is extruded from the extrusion opening of the extrusion nozzle of the extruder, is cut by a cutter of a cutter wheel that is rotating, and is separated away from the extrusion opening. The synthetic resin that is separated away is supplied to synthetic resin-holding means provided on the cutter wheel. The holding means holds the synthetic resin, and releases the holding state, permitting the synthetic resin that is held to fall down.
The compression-forming machine is so arranged that the mold (female mold) comes in contact with a rotary orbit of the holding means. The synthetic resin held by the holding means is moved to a position over the mold of the compression-forming machine, discharged downward (permitted to fall down) as the holding means is released, and is supplied into the mold. Here, the position of the holding means is brought into agreement with the position of the mold to supply the molten resin. In the compression-forming machine, the synthetic resin supplied to the female mold is compression-formed in cooperation with the male mold provided for the compression-forming machine to thereby form a preform of a desired shape. JP-A-2000-108127 discloses an apparatus that separates the synthetic resin in a molten state away from the extrusion opening of the extrusion nozzle and supplies it to the compression-forming machine. JP-A-62-3926 and JP-UM-B-6-27372 are disclosing devices for separating away a synthetic resin in a molten state in a hollow blow-forming machine and in a plastic granulating machine.
A metal mold wheel continues to rotate at a constant speed while a cutter wheel remains at rest at the start of the operation until the molten resin discharged from the extrusion opening of the extruder assumes a stable state. When a state is reached where the molten resin is discharged at a constant rate maintaining stability, a motive power source and a clutch are connected together causing the cutter wheel to instantaneously rotate at an outer circumferential speed in agreement with that of the metal mold wheel.
Problem does not arouse much when the metal mold wheel is rotating at a low speed. When the metal mold wheel is rotating at a high speed to meet the requirement of high-speed molding, however, the cutter wheel is brought into agreement with the rotational speed of the metal mold wheel requiring an extended period of time and causing an increased load. In order to instantaneously drive and rotate the cutter wheel, therefore, it becomes necessary to use the motor and the clutch having increased driving forces.
The present invention was accomplished in view of the above-mentioned circumstances, and has an object of providing an apparatus for cutting and supplying synthetic resins, which can meet the trend for revolving the metal mold wheel at a high speed, and can be applied to the metal mold wheel that rotate at a high speed yet using a motor and a clutch of small driving forces.